Vanillin is one of the major components constituting vanilla extract, which is a powerful natural aroma obtained from the bean of an orchid. The extraction of this molecule from vanilla beans is very expensive; the quantities produced are limited and do not cover market demand. Other ways of obtaining vanillin have been sought.
It is for example possible to obtain vanillin from ferulic acid by bioconversion reaction with bacteria. In this patent application, we are interested only in the ferulic acid bioconversion pathway of vanillin by bacteria.
Vanillin production by bacteria is done by deacetylation of ferulic acid by means of the following 3 steps:
1. Activation of ferulic acid in feruloyl-CoA, activation being catalysed by an enzyme, the feruloyl-CoA ligase, hereinafter FCS;
2. Hydroxylation of the feruloyl-CoA in 4-Hydroxy-3-methoxyphenyl-P-hydroxypropionyl-CoA, hydroxylation being catalysed by an enzyme, Enoyl-CoA Hydratase/Aldolase, hereinafter ECH;
3. Deacetylation of the 4-Hydroxy-3-methoxyphenyl-β-hydroxypropionyl-CoA allowing vanillin to be obtained, also catalyzed by the enzyme ECH.
The vanillin obtained can subsequently be oxidized to vanillic acid by an enzyme, vanillin dehydrogenase, hereinafter VDH. However, converting vanillin to vanillic acid is not desired because only the vanillin has the desired aromatic characteristics.
According to the EC nomenclature of the enzymes (Enzyme Commission number):                the enzyme FCS has the code EC 6.2.1.34,        the enzyme ECH has the codes EC 4.2.1.101 and EC 4.1.2.41,        the enzyme VDH has the code EC 1.2.1.67.        
EP 2 721 148 A1 describes a microorganism of the genus Amycolatopsis not comprising the gene encoding the VDH, said microorganism making it possible to produce vanillin from ferulic acid.
EP 1 611 244 A1 describes a vanillin production process that does not use organic solvents during purification, as they are now considered undesirable in the food industry, to obtain a vanillin called “natural.” During said vanillin production process, the biotransformation of ferulic acid into vanillin is performed by the Amycolatopsis strain IMI390106, also called the Zyl 926 strain or the Amycolatopsis Zyl 926 strain.
The book “Practical Streptomyces Genetics”, 2000, Kieser, et al. published by The John Innes Foundation, ISBN 0-7084-0623-8, in Chapter 10, describes a method of transfer between Escherichia coli and Streptomyces for DNA integration at specific sites.
However, the strains of the prior art used in the bioconversion reaction do not allow an optimal conversion of ferulic acid to vanillin. Given the cost of ferulic acid, there remains a need for new strains of bacteria ensuring better conversion of ferulic acid to vanillin.